1. Field of the Invention
The present invention relates to a device for supplying a liquid coating or ink in a state of thin-film in relief printing machines, a liquid coating supplying device in die bonders, etc.
2. Prior Art
Conventional thin-film supplying devices include, for example, a device disclosed in Japanese Patent Application Laid-Open (Kokai) No. 3-43250 which is shown in FIG. 7.
This device includes a printing plate 1 which has a recessed area 1a formed in its upper surface, a table 2 which holds the printing plate 1, a pot holder 3 which is installed above the printing plate 1 in a vertically movable manner, and an ink pot 4 which is held by the pot holder 3. The ink pot 4 consists of a tank 6 which accommodates a liquid coating or ink 5, a cover 7 which covers the top of the tank 6, and a blade 8 which is attached to the bottom of the tank 6. A circular recessed liquid reservoir 8a for storing the ink 5 therein is formed in the undersurface of the blade 8.
When the table 2 moves horizontally to the right or in the direction indicated by arrow A as shown by the two-dot chain line after the ink pot 4 has been lowered and the bottom of the blade 8 is pressed against the printing plate 1, the ink 5 inside the ink reservoir 8a uniformly fills the recessed area 1a of the printing plate 1.
Next, a plate holder 10 is lowered as shown by the two-dotted chain line; as a result, a rubber relief plate 11 on the plate 10 contacts the ink 5 in the recessed area 1a so that ink 5 is applied to the rubber relief plate 11. The plate holder 10 is raised, and the table 2 is moved back horizontally to the left in the direction indicated by arrow B. Afterward, the plate holder 10 is further lowered as indicated by the two-dot chain line so that the rubber relief plate 11 is pressed against the object 12 on which printing is to be performed. Thus, the ink 5 on the undersurface of the rubber relief plate 11 is transferred to the object 12. The plate holder 10 then returns to its original position.
In the prior art described above, the ink pot 4 is provided on the pot holder 3 via four adjustment screws (not shown) which are attached to the pot holder 3 on the left, right, front and back and adjusted so that the undersurface of the blade 8 is maintained parallel to the printing plate 1. As a result, the blade 8 may be loosened by wear that occurs during the horizontal movement of the printing plate 1, which causes the ink 5 to leak from the ink reservoir 8a. When the printing plate 1 moves in the direction of B, a rotational moment acts on the blade 8 in the direction of arrow C, so that the leading-edge undersurface 8b of the blade 8 floats upwardly. In other words, ink 5 is scraped off by the trailing-edge undersurface 8c of the blade 8, and ink 5 in the ink reservoir 8a leaks from the leading-edge undersurface 8b of the blade 8, which is not in contact with the printing plate 1. As a result, the amount of ink 5 consumed is increased.
Furthermore, since the undersurface of the blade 8 is round, the application of a rotational moment in the direction of arrow C results in that the blade 8 contacts the printing plate 1 at one point only, with the remaining parts of the blade 8 kept above the printing plate 1. As a result, when the blade 8 moves and scrapes the upper surface of the ink 5 that has accumulated in the recessed area 1a, the ink 5 is scraped by various parts of the undersurface of the blade 8 which are at different heights, and a thin film of ink 5 is not uniformly supplied to the recessed area 1a.
In addition, when adjusting the blade 8 to contact the printing plate 1 without any gap between the two, it is necessary to turn the four adjustment screws of the pot holder 3 so that the undersurface of the blade 8 is parallel to the upper surface of the printing plate 1. The adjustment work for obtaining this parallel orientation, however, requires considerable time.